I thought this was a very interesting reflection by bret Contreras on the issue of pelvic tilting in certain exercises
Click here
the only thing id add is that i feel the  Mcgill and Verkoshansky V  Mel Siff . is   a bit contrived. I think they deal with different types of people with different out puts.
“The pelvis plays a vital role in the ability of the athlete to produce strength efficiently and safely, because it is the major link between the spinal column and the lower extremities… a neutral pelvic tilt offers the least stressful position for sitting, standing and walking. It is only when a load (or bodymass) is lifted or resisted that other types of pelvic tilt become necessary. Even then, only sufficient tilt is used to prevent excessive spinal flexion or extension… The posterior pelvic tilt is the appropriate pelvic rotation for sit-ups or lifting objects above waist level. Conversely… the anterior pelvic tilt is the correct pelvic rotation for squatting [and] lifting heavy loads off the floor. – Supertraining 2009 (Hat tip to Pavel Tsatsouline for finding this quote)”
Bret believes this: “I’ve learned much of my spinal biomechanics knowledge from Stu and highly respect him. In this case, I feel that some slight pelvic tilt can help buttress the spine by creating torque in the necessary direction in order to help stabilize the spine and prevent buckling. However, the pelvic tilt isn’t to end-range so it doesn’t dramatically impact spinal posture, but rather keeps it in check”
The difference in the opinion is probably a matter of perspective  and  objective. McGills observation ( and I’m a Mcgill fan) is that bad backs are correlated with poor back control and use. back pain is the result of years of systematic abuse. His battle is to get clients to learn or relearn back positions.
Verkoshansky and Mel Siff are not trying to cure your bad back, they are trying to get you to lift more. For  advanced athletes who do not suffer back pain, their approach is great.
For people who do suffer back pain, getting an effective general purpose  healthy motor pattern is far more important.

We are probably going to change the name within a few months, but, for now, look out for the daily MWOD’s or Mind Workouts of the Day.
At the Backaholic programme  we are excellent physical trainers:  our expertise, programming and experience combined with  your commitment  hard work often means we can deal with back pain.
We are always looking to improving our coaching techniques and training methods, so our trainers continue their ongoing education, to keep up to date, to spot new effective training ideas  to ensure we offer the best service  in London and to be true to their  personal values of being the best   back fixers  around
However, Many of our  trainers have reported that often the physical targets set by you are undermined by peripheral factors : lack of sleep, poor diet,  negativity,  disrupted attitudes,  undermining self talk, a lack of belief, being too  self critical  perfectionist thinking and, sometimes  a lack of spirit
The reality is that if you look for the bad in everything,  you come training under an emotional cloud.
Negativity  effects everything you do.
Many of our clients, in their professional lives are paid to critically appraise business processes: political movements, accounts and marketing strategies.  Improvements,  after all,  can only be made by identifying where  improvements can be made.
You can see  an opportunity to improve your techniques, strength mobility as  fantastic  and useful challenge, or you can obsess about how poor your technique is , how poor your mobility is and how weak you are.
Negative thinking escalates and undermines everything.
Being aware of where you need to improve and  having a positive plan with  the ability to break things down, to understanding and cope with failure and be positive,  is the “secret” of successful people. This obviously relates to how you think about things, your attitudes, who you hangout with and whether the team that surrounds you helps or hinders you.
All these ideas and more will  explore on a daily, bit sized basis. Sometimes it will be simple reflections, other times considering the words of the wise,  often simple review tasks. Wait and see. What and how we cover these topics will change over the months but hopefully we will be able to wrestle  some of the cooler techniques away from the tree hugging hippies!
For today some lines from Satoru Izumi’s book ” Guidelines of Faith”
“fundamentally, everyone wants to be happy. The key to attaining happiness lies in whether we can overcome the negative influences of our environment or whether we will be defeated by them. Think of seeds,  the harder it is trodden under , the stouter  the seedling that grows… this holds true with human development… each of us has the seed of happiness. It is covered with the “earth”of various  problems which motivate us”